This concentrates in one line all the explanation we have just gone through. : . '.. •
Sometimes the slag has a sufficient supply of oxide of iron and needs no more. In this case, when ore is added, all the oxygen goes to the carbon of the bath so that there are three atoms of oxygen calling for three atoms of carbon. This leaves the iron alone in its metallic state and it is instantly dissolved in the hath, and the weight of the charge is increased by just so much. The chemical symbol expressing this is as follows:
Generally it will happen that the truth lies between these two conditions; that the slag keeps part of the oxide and the rest is reduced, part of the oxygen uniting with carbon and part of the iron being dissolved in the bath, the remainder of the oxide of iron entering the slag.
Still another condition exists whenever iron ore is not 'added to the bath. Under this state of affairs, it may be necessary for the slag to have more oxide of iron, and there is no place for this to come from except the bath. Therefore, when there is need of oxide of iron, the iron of the bath unites with the oxygen of the flame and goes into the slag. .
Thus it is clear that if no iron ore is used, a certain equivalent amount of good stock must be oxidized, and that if iron ore is used the weight of metal tapped will be greater than if it had not been added. . .,.-.•
The amount of carbon in the steel, and therefore the tensile strength, depends entirely on the conduct of the operation, but the amounts of phosphorus and sulphur depend upon the kind of stock which is put into the furnace. If a superior .quality of steel is required the original stock should contain only small percentages of these elements. Such stock, however, costs more money than common scrap. If an ordinary quality is required then ordinary pig-iron and scrap are used.
It is a common belief that it is an easy thing to distinguish between open-hearth .steel and Bessemer steel. It is usually very easy to tell basic open-Hearth steel from acid Bessemer, or acid open-hearth from basic Bessemer, but it is impossible by any ordinary means to tell acid Bessemer from acid open-hearth or basic Bessemer from basic open-hearth.. Most American metallurgists